Helpful hint for myself

flake.nix

@@ -95,6 +95,8 @@
             echo "Configure Command: "
             echo -n '  LDFLAGS="-L$MPS_LIB" CFLAGS="-O0 -g3 -isystem $MPS_INC" '
             echo './configure --with-mps=debug --with-native-compilation=no --enable-checking="yes,glyphs"'
+            echo "If you are using Emacs from emacs-overlay, remember to unset environment variable EMACSLOADPATH"
+            echo "Need to investigate further as to why"
           '';
         };
       };